It is often desired to roll a thread onto a workpiece. There are a number of ways of doing this. In some cases, thread rolls are moved tangentially into engagement with the cylindrical surface of a workpiece onto which a thread is to be rolled. In other instances, the thread rolls are moved axially into position along side the workpiece, and are then moved radially inwardly to engage the workpiece and to roll the thread thereon.
According to still another technique, an attachment is provided on a machine tool. The attachment has three thread rolls that are movable radially between engaged and disengaged positions. Initially, the three thread rolls are moved radially inwardly to an engaged position. The workpiece is then feed axially into the space between the three rolls, either through movement of the workpiece relative to the attachment or vice versa, and a thread is progressively rolled onto the workpiece. When the end of the workpiece abuts a stop, a triggering mechanism causes the spring-biased thread rolls to quickly move radially outwardly so as to disengage themselves from the workpiece and to allow the workpiece to be withdrawn from the attachment.
One such type of end working attachment is shown and described in U.S. Pat. No. 5,568,743, which issued on Oct. 29, 1996 to Wilhelm Fette GmbH. This patent discloses in FIG. 1, a conventional prior art end working attachment of the type heretofore described.
Other types of thread rolling attachments and implements are shown and described in U.S. Pats. No. 2,909,087, 3,352,139, 3,365,924 and 4,771,625. The disclosure of all five of the above patents is hereby incorporated by reference insofar as their descriptions of the structure and operation of prior art thread rolling attachments is concerned.
Upon information and belief, one problem that accompanies the use of the device shown in FIG. 1 of the Fette '743 patent, is that the front plate is relatively thin and flexible, and may distort in use. This can adversely affect the shape and profile of the threads that are rolled onto a workpiece.
Accordingly, it would be generally desirable to provide an improved thread rolling attachment of the same general type, that would have increased rigidity, and would be less susceptible to distortion.